The present invention relates to a refrigerating apparatus, and more particularly to a refrigerating apparatus that performs a control of refrigerating capability for use in an air-conditioning system or the like.
In recent years, there is a tendency that a refrigerating apparatus having an electromotive compressor variable in operation speed by means of an inverter and an electromotive expansion value is employed in such an equipment as an air conditioning system or the like. This refrigerating apparatus is adapted to change the amount of a refrigerant flowing through the refrigeration cycle by controlling, the operational speed of the compressor and/or the valve opening degree of the expansion valve, and can more finely control its refrigeration capability in comparison with conventional refrigerating apparatuses.
The refrigerating apparatus of such type is disclosed in, for example, Japanese Utility Model Unexamined Publication No. 59-52359, Japanese Patent Unexamined Publication No. 61-285349 and Japanese Patent Unexamined Publication No. 62-52367.
Japanese publication No. 59-25359 proposes the refrigerating apparatus in which whenever the apparatus is started to operate, the electromotive expansion valve is once set to a predetermined valve opening degree for starting the operation, and thereafter, the opening degree of the expansion valve is adjusted in response to an operational or driving frequency of the compressor. In Japanese publication No. 61-285349, there is shown the refrigerating apparatus in which a driving frequency of the compressor is changed within an operational range except when the compressor is operated at a minimum operational frequency, and the opening degree of the electromotive expansion valve is changed when the compressor is operated at the minimum frequency, so as to change the refrigeration capability. Japanese publication No. 62-52367 discloses the refrigerating apparatus in which a valve opening degree of the variable capacity type expansion valve is changed in response to an operational frequency of the compressor to thereby regulate a suction pressure of the compressor.
Any one of the above-described apparatuses would contribute toward improving the controllability of the refrigeration cycle or enlarging the variable range of the refrigeration capability thereof. However, for instance, in order to use the refrigerating apparatus in an air-conditioning system and perform more comfortable air-conditioning, it is desirable to more increase the variable range of the refrigeration capability of the apparatus by increasing the operational range thereof while enabling the apparatus to operate in a stable and continuous manner.